JPH1048500A - Optical apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical apparatus capable of position control of a moving lens group, which can detect temp. with high accuracy in spite of having a simple structure and is not affected by an environmental temp. change, by providing the apparatus with an arithmetic means which calculates temp. change rate by using the absolute temp. value, etc., to be reference, and supplying these values to a movement control means for a moving lens. SOLUTION: The ambient temp. at the time of apparatus assembly is written as a reference value as the absolute temp. into an EEPROM 112 and simultaneously the temp. in a temp. detecting sensor 110a is detected as a relative temp. value and is written therein. When a power source is turned on after shipping, the work is thereafter executed automatically. The 110 a output from the temp sensor of the temp. detecting means is read into a microcomputer 120 and is stored in a memory means 123d. Next, the reference value of the absolute temp. and the relative temp. value already read into the EEPROM 112 are fetched. These values, the relative temp. value stored in the memory means 123d and the information from the temp. detecting sensitivity 122a are drawn out and are subjected to computation, by which the temp. change rate is calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to optical devices such as video cameras, silver halide cameras, electronic still cameras, and binoculars.

[0002]

2. Description of the Related Art In recent years, the cost of cameras and the like has been reduced, and plastic materials having a large cost merit may be used as lens materials constituting a photographic optical system. A plastic material has a larger optical constant such as a refractive index with respect to a temperature change than an inorganic glass material, and, for example, a focal length and the like greatly change due to a temperature change as compared with an inorganic glass material.

For this reason, temperature detection means such as a temperature detection sensor must be provided in the lens barrel, and the lens control means must detect the temperature change and control the lens so as to cancel out the temperature change of the optical constant of the lens. However, since plastic lenses have been used in some cameras in the popular price range where high-precision focal length control is not required, high-precision temperature detection is not required for temperature detection. I just needed to be detected.

[0004] However, in the future, even if plastic lenses are increasingly used and inorganic glass materials are used,
High-precision temperature correction control is required for a shooting optical system of a high-end device requiring high image quality such as a digital video camera. For this reason, high-precision temperature detection has been required for the temperature detection accuracy.

Conventionally, if temperature detection is to be performed with a detection accuracy of, for example, ± 2 ° C., sensitivity adjustment of a temperature detection sensor and offset adjustment and gain adjustment of a temperature detection circuit are required.
Further, the temperature environment at the time of the adjustment has to be strictly set.

FIG. 5 shows a conventional temperature detecting means, which will be described in more detail. Reference numeral 511 denotes a stabilized voltage source; 501, a temperature-sensitive resistor whose resistance value changes according to a temperature change; 509, an operational amplifier that outputs a temperature detection result; and 510, a preamplifier serving as an amplifier.

[0007] The output of the preamplifier 510 here becomes the detected temperature value.

[0008]

As a temperature detecting sensor, for example, if a constant current of 1 mA is passed through a temperature-sensitive resistor 501 having a resistance value of 1 kΩ at a temperature change rate of about 5000 ppm / ° C., the temperature detecting sensor becomes a sensor. Temperature resistance 501 is 5mV
/ ° C, but in order to suppress the sensitivity error, the resistance volume 50
3 requires fine adjustment of the sensitivity of the temperature detection sensor. or,
In the latter stage preamplifier 510, the final detection accuracy of the temperature detecting means must be increased while finely adjusting using the gain adjustment resistor volume 507 and the offset adjustment resistor volume 508, and the adjustment process for detecting the ambient temperature and its environment Setting was very troublesome. In the figure, 505 and 506 are gain resistors and 512 is an output terminal.

[0009]

According to a first aspect of the present invention, there is provided a temperature detecting means for detecting a temperature, a temperature sensitivity of the temperature detecting means, and the temperature detecting means when a reference absolute temperature value is detected. Storage means for storing a first detected temperature value obtained from the temperature detection means, and at least a current second detected temperature value, the first detected value, the temperature sensitivity, and the reference absolute value which are detected by the temperature detecting means. Calculation means for calculating a temperature change amount from the first detection temperature to the second detection temperature using the temperature value, and supplying the amount of change to the control means for controlling the movement of the moving lens according to the temperature change. An optical device having:

A second aspect of the present invention is characterized by an optical device in which the ambient temperature at the time of assembling the device is set as a reference absolute temperature.

According to a third aspect of the present invention, as the temperature detecting means,
An optical device using a positive or negative linear sensitivity is characterized.

According to a fourth aspect of the present invention, by adding the reference absolute temperature value to a value obtained by dividing a difference value between the second detected temperature value and the first detected temperature value by the temperature sensitivity, An optical device for performing an operation for obtaining the temperature change amount is characterized.

[0013]

FIG. 1 is a block diagram showing an optical apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 1 denotes an optical system of a video camera, which comprises a rear focus zoom lens group (hereinafter, referred to as RFZ) including four lens groups. RFZ1 denotes a first lens 101 which is a fixed lens group, a second lens 102 which is a moving lens group and performs a variable power function, a third lens 103 which is a fixed lens group,
Further, it has a fourth lens 104 which is a moving lens group and has a focus function and a function as a compensator for correcting an image plane variation due to zooming. At least one lens is formed of plastic.

Reference numeral 105 denotes subject light passing through the optical system,
It is a photoelectric conversion element such as a CCD which is converted into an electric signal.
The temperature detecting means has a temperature detecting sensor 110a and a preamplifier 110b. The temperature detection sensor 110a is capable of linearly detecting the temperature, and is, for example, a semiconductor temperature sensor that detects the temperature from the temperature coefficient of a silicon semiconductor such as a temperature-sensitive resistor or a transistor or a diode made of a mixed material of manganese and cobalt. And so on.

The temperature detecting sensor 110a is a photoelectric conversion element 1
It is arranged inside the lens barrel around the lens, which is more than 05 away, or on the outer surface of the lens barrel. In this embodiment, one temperature detection sensor 110a is used. However, a plurality of temperature detection sensors 110a may be used to calculate the average value of the detected temperatures, or the temperature of each lens may be detected.

Further, the temperature detecting sensor 110a is not limited to the above-described temperature-sensitive resistor or semiconductor temperature sensor.
Other types of temperature detection sensors may be used.

If the temperature sensitivity K of the temperature detecting means is calculated by the following equation, it can be constructed inexpensively.

K = (Vsh−Voff−VSoff) / Tsh (1) where Vsh is an active voltage range of the preamplifier 110b,
Voff is the offset amount of the preamplifier 110b, VSo
ff represents an offset amount of the temperature sensor, and Tsh represents a detected temperature range.

Since the power supply of the temperature detection circuit and the control system is a 5 V system and the preamplifier used is generally a low-cost general-purpose operational amplifier, the active voltage range of the general-purpose operational amplifier is 0.6 V to 3.5 V. V is the preamplifier 110b
, The offset amount of the temperature sensor and the preamplifier 110b is about 0.8 V, and the operating temperature of the video camera
Considering 10 ° C. to + 60 ° C., the temperature sensitivity of the temperature detecting means is desirably approximately 30 mV / ° C. from the above equation.

In the case of a 3V power supply, the preamplifier 1
Even when a C-MOS operational amplifier having a wide active voltage range and capable of operating at a low voltage is used for 10b, it is desirable that the temperature sensitivity of the temperature detecting means be approximately 30 mV / ° C. K matches. At this time, the gain G of the preamplifier 110b is calculated by the following equation.

G = K / K ′ (2) Here, the temperature sensitivity K of the temperature detecting means is 30 mV / ° C., and the temperature sensor sensitivity K ′ differs depending on the type and the design method of the temperature detection sensor 110a. 5mV / ℃
〜１０10 mV / ° C.

The output value from the temperature detecting means 110 includes an offset component, and the offset adjustment is not necessary in the present embodiment, so that the temperature value obtained here is a relative temperature value.

Reference numeral 112 denotes a reference value Tref, which is the absolute temperature of the surroundings at the time of shipment adjustment detected by the accurate temperature detecting device, and a relative value, which is the output voltage value of the preamplifier 110b representing the temperature obtained from the temperature detecting means 110 at that time. This is a second storage unit such as an EEPROM that stores the temperature value dto as an absolute temperature.

Reference numeral 120 denotes a control means such as a microcomputer (hereinafter referred to as a microcomputer). The A / D converter 121 takes in the output voltage of the preamplifier 110b, which is a relative temperature value, into the microcomputer 120, and temperature sensitivity data of the temperature detection means. 122a, a temperature correction value 122b of the lens to be controlled, and a stop position on the optical axis of the second lens 102 and the fourth lens 104 (hereinafter referred to as a cam locus) for maintaining focusing at each subject distance and each focal length as shown in FIG. dcz) Data 12
2c, a first storage unit 122 such as a ROM,
A temporary storage means 124 such as a RAM for temporarily extracting data from the storage means 112 and temporarily storing the data;
2nd lens group 1 according to the program procedure written in
02 and the fourth lens group 104 etc.
And MPU 123c for executing an operation for drive control via an actuator such as a stepping pulse motor
Consists of

The MPU 123c stores the temperature sensitivity data 1 of the temperature detection means 110 stored in the first storage means 112.
22a, the lens temperature correction value 122b, and the absolute temperature reference value Tref stored in the second storage means 124.
From the relative temperature value dto at the time of reading the reference value and the numerical value of the voltage dt1 representing the observed relative temperature measured at regular time intervals, an operation for controlling the lens position such as the focus 123a or the zoom 123b is performed.

In FIG. 3, for example, when the subject distance is infinity and the second lens 102 moves on the optical axis from the WIDE direction to the TELE direction, the fourth lens 104 has a locus convex toward the object side on the optical axis. Move along curve Y #. When performing zooming in this manner, the second lens 102 and the fourth lens 104 are driven and controlled so as to trace the cam trajectory according to the subject distance, so that there is no out-of-focus.

Next, FIG. 2 is a flowchart showing the operation of the present embodiment. At the time of assembling the equipment at the factory, the power is turned on at the time of adjustment work for performing various adjustments, and the operator stores the ambient temperature at that time in the EEPROM as the storage means 112 as an absolute temperature (a temperature detection device different from the temperature detection sensor 110a). To detect the more accurate absolute temperature) with the reference value Tre
f, and at this time, the temperature detection sensor 1
10a, the temperature is detected, and the output voltage △ dt0 amplified by the preamplifier 110b is temporarily stored in the storage means (EEPROM) 1 as the relative temperature dt0 via the microcomputer 120.
12 and the power supply is stopped (S201 → S202).
→ S203 → S204).

After the shipment, when the power is turned on again, the program in the microcomputer 120 starts to operate, and thereafter the work is automatically performed. A relative temperature detection value from the temperature detection means, that is, an output voltage △ dt1 obtained by amplifying the output from the temperature sensor 110a via the preamplifier 110b is read into the microcomputer 120 through the A / D converter 121 continuously for a predetermined time, and In order to increase the accuracy of the value, the output voltage △ dt1 as a relative temperature value is averaged and stored in the storage unit 123d (S206).

Next, an EEPROM serving as the storage unit 112
The reference value Tref of the absolute temperature already written in
Then, the relative temperature value dt0 is extracted and temporarily stored in the RAM 124 area. These values, and R
Information is extracted from the temperature detection sensitivity 122a stored in the OM, and the following equation is calculated to calculate a temperature change amount ΔT.

ΔT = (dt1−dt0) K + Tref (3) Here, the temperature change ΔT is converted from a relative temperature value to an absolute temperature value (S207 → S208).

Next, the second lens 102 and the fourth lens 1
The position of the position 04 is detected, and the position data ZD and FD are stored in the RAM area 124 in the microcomputer 120. If stepping motors 133 and 134 are used as actuators for the movable means of the second lens 102 and the fourth lens 104, the position can be easily detected only by counting the number of driving pulses. For example, a DC motor and an encoder are used. Other lens driving methods and lens position detection methods may be used. (S209 → S210)

Next, the second lens 102 and the fourth lens 1
The temperature correction coefficient value α corresponding to the position data ZD, FD of No. 04 is extracted from the ROM area 122b as the first storage means, and the lens drive correction amount β is calculated by the following equation.
24 (S211).

Β = α * △ T (4)

Since the temperature correction coefficient value α differs depending on the mutual positional relationship between the second lens 102 and the fourth lens 104 as shown in FIG. 4, a plurality of temperature correction coefficient values α are stored in the ROM area 122b. Is stored.

Next, the cam locus data dcz stored in the ROM area 122C is extracted, and the temperature correction coefficient value α
Is added, the cam locus data dcz is corrected, and the appropriate positions MZ,
MF is required. The obtained appropriate positions MZ and MF of the second lens 102 and the fourth lens 104 are calculated by the calculating means 123.
a, 123b, and is output to each of the drive circuits 131, 132, and is used as a stepping motor 133, 1
34, the second lens group 102 and the fourth lens group 1
04 moves to a position where focus is maintained (S212 → S2)
13).

The above operation is repeated until the power is turned off, and the position of each moving lens group is constantly corrected and controlled with respect to the environmental temperature change (S214).

[0037]

According to the first aspect of the present invention, the offset occurring in the temperature detecting means is canceled, the temperature can be detected with high accuracy even with a simple structure, and the moving lens group which is not affected by the environmental temperature change. An optical device capable of position control can be provided.

According to the second aspect of the present invention, in addition to the above effects,
An optical device capable of accurately responding to a temperature change from the time of lens position adjustment during assembly can be provided.

According to the third aspect of the present invention, in addition to the above effects,
It is possible to provide an optical device that can cope with a minute temperature change.

[Brief description of the drawings]

FIG. 1 is a block diagram of an optical apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart showing the operation of the optical apparatus shown in FIG.

FIG. 3 is a diagram showing a cam locus of the moving lens of FIG. 1;

FIG. 4 is a diagram showing a correlation between each lens position and a temperature correction coefficient α.

FIG. 5 is a diagram showing a conventional temperature detecting means.

[Explanation of symbols]

 102 moving lens 104 moving lens 110a temperature detection sensor 120 microcomputer

Claims (4)

[Claims] 1. An optical apparatus comprising: an optical system including a plurality of moving lenses; and driving means for driving the plurality of moving lenses; and control means for performing different control of movement of the moving lenses according to a temperature change. A temperature detecting means for detecting a temperature, a temperature sensitivity of the temperature detecting means, and a memory for storing a first detected temperature value obtained from the temperature detecting means when a reference absolute temperature value is detected. Means, at least a second current state detected by the temperature detecting means.
And calculating the temperature change amount from the first detected temperature to the second detected temperature using the detected temperature value, the first detected value, the temperature sensitivity, and the reference absolute temperature value. An optical device, comprising: an arithmetic unit for supplying to a control unit. 2. The optical device according to claim 1, wherein the reference absolute temperature is an ambient temperature when the device is assembled. 3. The optical apparatus according to claim 1, wherein said temperature detecting means has a positive or negative linear sensitivity. 4. The arithmetic means adds the reference absolute temperature value to a value obtained by dividing a difference value between the second detected temperature value and the first detected temperature value by the temperature sensitivity, thereby obtaining the reference absolute temperature value. 4. The optical apparatus according to claim 1, wherein the temperature change amount is obtained.